Field of the Invention
The invention relates to a printing machine and an appertaining printing process. In offset printing, ever-greater parts of the operations for producing the printing form, the so-called pre-press stage, are performed with the assistance of electronic data processing. In the so-called computer-to-plate technique, all the operations from the production of the page layout to the digitally controlled imaging of the printing plate occur in the computer. The imaging of the printing plates takes place separately in a special exposure unit. In the so-called computer-to-press/direct imaging technique, as has been applied for the first time by Heidelberger Druckmaschinen AG in the GTO-DI, the exposure unit is transferred into the printing machine. The plates are exposed on the cylinder directly in the printing machine.
With regard to digital printing, techniques which go even further, also referred to as computer-to-print and computer-to-paper, include transferring digitized data from a computer to paper or other printing materials without a printing form with a fixed image via an intermediate carrier (e.g. photoconductor) or without any material intermediate stage. Corresponding printing techniques are, for example, electrophotography, thermal transfer printing or ink-jet printing and allow the motif to be changed during continuous printing, for example to produce a new printed image with each revolution of a form cylinder. In this regard, the production of a printing form is dispensed with, because each individual printing image is newly provided. However, this sacrifices the advantage of conventional processes such as offset printing, for example, of being able to print with high productivity from a constant printing form and of ensuring very high quality over the print run or edition.